Aerys II Targaryen, popularly called "the Mad King", is an unseen character in Game of Thrones. Deceased prior to the events of the series, Aerys Targaryen was the last member of House Targaryen to rule from the Iron Throne. Although his rule began benevolently, he succumbed to madness and was eventually deposed by Robert Baratheon in a civil war. Infamously, Aerys was murdered by a member of his Kingsguard, Ser Jaime Lannister, earning the latter the sobriquet "Kingslayer".

Aerys's two surviving children, Viserys and Daenerys, were taken to the Free Cities of Essos, intent on one day returning to Westeros to reclaim what they regard as their birthright. He was formally styled as Aerys of House Targaryen, the Second of His Name, King of the Andals and the First Men, Lord of the Seven Kingdoms and Protector of the Realm.

Aerys had already instructed Wisdom Rossart, now his Hand of the King, to hide caches of wildfire all over King's Landing. Now, he decreed that the capital be set ablaze. Aerys seemingly believed the massive inferno would transmute him into a dragon and he would emerge to obliterate his enemies. To prevent the King incinerating the city and its half a million inhabitants, Ser Jaime Lannister, a member of the Kingsguard, stabbed Aerys in the back and then cut his throat.[2]

Aerys's death brought to an end the Targaryen dynasty, which had ruled the Seven Kingdoms for three centuries. He was replaced on the Iron Throne by the leader of the rebels, Robert Baratheon. Aerys was survived by his two youngest children, Viserys and Daenerys, who were spirited away to the Free Cities.

When Lyanna Stark was kidnapped by Prince Rhaegar Targaryen, her brother Brandon rode to King's Landing to demand his sister's return. Aerys imprisoned Brandon and ordered that his father Rickard Stark ride south to answer for his son's impertinence. Against advice, Rickard agreed, assuming that the matter would be settled through a trial or a bargain of some kind. Instead, Aerys had Lord Rickard burned alive while Brandon watched, and then had Brandon strangled.[4]

Bored and attempting to mock Ser Jaime, King Robert realizes that he never asked Jaime what King Aerys Targaryen's last words were, then taunts Jaime for killing a defenseless old man he had sworn to protect. Jaime tersely responds that the last thing the Mad King said was the same thing he'd been raving for hours, since the sack of the capital by the rebels began: "Burn them all!" This silences Robert's levity.[8]

Maester Aemon reveals that he is the uncle of King Aerys and because of his oath to the Night's Watch could not interfere during the rebellion.[9]

Grand Maester Pycelle recalls that King Aerys was actually a good man, at least at first. He then laments that he saw Aerys melt away before his eyes, as madness increasingly gripped his mind over the years and a once charming man was consumed by dreams of fire and blood.[10]

Wisdom Hallyne of the Alchemists' Guild mentions Aerys as a fervent supporter of the guild. Aerys became obsessed with Wildfire in his later years. He reminds Bronn that he would not have dared to insult the guild while Aerys was alive.[11]

As the Targaryens were losing the war, Aerys had his pyromancers place caches of wildfire all over King's Landing: under the Great Sept of Baelor, under the slums of Flea Bottom, under houses, stables, taverns, and even under the Red Keep itself. After Robert's victory at the Trident he marched on the capital city, but Jaime's father Tywin arrived there first, leading the entire Lannister army, and promising to defend the city. Jaime warned Aerys that his father was never a man to choose the losing side, that this must be a trick and he should surrender the city while he still could, but the Mad King refused to listen. Nor did Aerys listen to Varys when he gave the same warning that Tywin couldn't be trusted - but he did listen to Grand MaesterPycelle, who convinced Aerys the Lannisters were there to help.

Aerys opened the city gates, and the Lannisters proceeded to sack the city. Jaime again begged Aerys to surrender, but the Mad King ordered Jaime to bring him Tywin's head, and his pyromancer (WisdomRossart) to set the city ablaze with the hidden wildfire, burning its five hundred thousand inhabitants to death, rather than lose the city to the rebels. "Burn them all," Aerys said, "Burn them in their homes. Burn them in their beds." Jaime makes it plain to Brienne that was his breaking point and asks her what she would do if her precious Renly commanded her to kill her own father and then stand by and do nothing as he murdered thousands of innocent people; she can only sit in shocked silence. Jaime goes on to say that he killed the pyromancer first, then drove his sword into Aerys' back as the Mad King tried to run for his life. Even as he was dying, the Mad King kept raving "Burn them all...Burn them all..." Shaken at the memory, Jaime speculates that King Aerys didn't believe he would die in the blaze; in his lunacy, the Mad King believed he would be reborn as a dragon in the fire, granting him the power to burn his enemies to ashes...so Jaime finished Aerys off by slitting his throat in order to make sure he died, concluding that Eddard Stark found him at that point.[12]

In the A Song of Ice and Fire novels, Aerys II's reign began with great promise. Taking the throne at only the age of 20, Aerys installed a number of younger, vigorous and capable men in positions of power, while his own son Rhaegar showed promise of being a great king in his turn. Aerys, impressed by the young Tywin Lannister's ruthlessness and effectiveness in crushing the Reyne Rebellion, made Tywin his Hand of the King. Tywin served very effectively as Hand for twenty years, during which the Seven Kingdoms prospered.

However, Aerys, who occasionally showed signs of a terrible temper, became erratic following the brief uprising known as the Defiance of Duskendale, when he was held prisoner for several months by a rebellious lord before finally being rescued by Barristan Selmy. Aerys's fury on that occasion was terrible: all of those involved in the incident were killed, several by being burned alive. After that, his rage could no longer be held in check.

Aerys's relationship with Tywin Lannister began to deteriorate in these later years, as Aerys grew ever more paranoid about Tywin's ambition. When Ser Ilyn Payne, captain of the guards for Tywin Lannister, made a joke that Tywin as Hand was the real ruler of Westeros, Aerys had his tongue cut out for the insult. Tywin could neither protest nor stop the punishment. The strains on their relationship were exacerbated by Aerys' well known lust for Tywin's wife Joanna Lannister, which the former crudely expressed during her bedding. His marriage with his own sister-wife, Queen Rhaella, which had never been happy (they were forced to marry against their will) became violent and abusive towards the end.

Over the years Aerys became increasingly gripped by madness, experiencing vivid hallucinations and delusional paranoia. Aerys became obsessed with fire, frequently burning his perceived enemies alive. Eventually, he was having women and babies roasted on spits in the throne room because the voices in his head told him they were plotting his ruin. Aerys would often become sexually aroused after burning someone to death, at which he would savagely rape his wife Queen Rhaella (his daughter Daenerys was the product of one such attack, quite possibly the same day he killed Rickard and Brandon Stark). Attempts to restrain Aerys' delusional behavior only fueled his paranoia that all were against him.

Aerys's growing madness took a drastic toll on his physical appearance. Fearful of allowing blades in his presence (save those of his sworn Kingsguard), Aerys ceased to have his hair or nails cut for years. By the time of the rebellion, his fingernails had grown nearly a foot long, and his long, filthy, tangled hair and beard hung below his shoulders. Increasingly paranoid that someone would attempt to poison him, he ate so rarely that he became extremely gaunt. Combined with the stress from his madness, by the time of the rebellion, when Aerys was only forty years old, he looked as old and haggard as a man twice his age. Due to his insane meanderings, he accidentally cut his hands and thighs so many times on the Iron Throne that they were practically covered in scabs, leading some to refer to him as "King Scab" behind his back.

Tywin had long hoped that Aerys would reward his service with a royal wedding, between his daughter Cersei and Prince Rhaegar. However, Tywin was infuriated when Aerys snubbed him by saying that Tywin was a mere servant of the crown, and no servant's daughter was fit to marry a prince of royal blood, and agreed to a marriage between Rhaegar and Elia Martell of Dorne instead. The last straw came when Aerys appointed Tywin's eldest son and heir Jaime Lannister to his Kingsguard. Normally this was the highest honor a knight could achieve, and Jaime himself was eager to accept, but it meant that Jaime had to forsake all claims as Tywin's heir (leaving his stunted and hated younger son Tyrion as his heir). Privately, Aerys had truly agreed to promote Jaime to the Kingsguard to keep him around the royal court at all times, essentially as an unwitting hostage in case Tywin ever decided to turn on him. Outraged by the continual insults he endured from Aerys, Tywin resigned as Hand of the King on some thin pretext; the Hands that followed were a succession of Aerys' cronies, who he later turned on for various failures, exiling or executing them depending on his whims.

After he burned several prominent lords alive and sanctioned his son's kidnap of Lyanna Stark, half of the realm rose in revolt against Aerys in Robert's Rebellion. Many who fought on the Targaryen side in the war weren't even fighting for the insane Aerys so much as for his promising son, Crown Prince Rhaegar. Indeed, one of the main reasons so many put up with Aerys' insanity for as long as they did was because they hoped they could simply wait out the few remaining years in Aerys' reign until Rhaegar took the throne, instead of having to face the serious moral dilemma of breaking their oaths against the currently ruling king. Robert Baratheon's victory over Rhaegar at the Battle of the Trident was therefore a double-blow to the Targaryen side: not only had the main royal army been defeated and scattered, but with Rhaegar dead, lords who had been on the fence decided to openly side with the rebels rather than fight for Aerys. Chief among these was Tywin Lannister himself, who had stayed out of the war until that point, who marched the 10,000 strong Lannister army to the gates of King's Landing, and once let inside, promptly began to sack the capital city.

Aerys's manner of death is slightly different from book to series. In the TV series, it is mentioned several times that Jaime stabbed him in the back, whereas in the book he slit Aerys' throat at the foot of the Iron Throne. It is never mentioned that Aerys ever said the words "Burn them all". However, the Season 3 episode "Kissed by Fire" brought Aerys's death closer in line to the books, when Jaime recounts to Brienne of Tarth that he stabbed Aerys in the back when he tried to run, and then Jaime proceeded to slit his throat to make sure he was dead.

Another change is that Eddard Stark was not the first to find that Jaime killed Aerys: before Jaime could leave and let some braggart take the credit/blame, Elys Westerling and Lord Roland Crakehall entered and saw him standing over Aerys's body. Crakehall was not surprised, figuring (incorrectly) that Jaime killed the king so the Lannisters could seize the throne. He asked Jaime, "Shall I proclaim a new king as well?" Jaime knew what he meant: either Tywin, or Robert Baratheon, or one of the surviving Targaryens. He considered for a moment to name either the boy Viserys or baby Aegon. But when he glanced down again at Aerys's body, he thought "his blood is in both of them". "Proclaim who you bloody well like" he told Crakehall. Then he climbed the Iron Throne and seated himself with his sword across his knees, to see who would come to claim the kingdom. As it happened, it had been Eddard Stark.

In a minor change from the books, Aerys II is said to be the son of King Aegon V Targaryen, rather than his grandson. His father, Jaehaerys II, appears to have been eliminated from the roll of kings. The reason for this appears to be to simplify the relationship between Maester Aemon - Aegon V's older brother - and the other Targaryens (by making Aemon Daenerys' grand-uncle, rather than great-grand-uncle).